Too bitter or too sour: A blind coffee taste tester's survival guide in optimising extraction

"Too bitter" and "too sour" are the two most common ways I hear people describe coffee. Particularly in China (the Chinese seem very sensitive to these flavours, or at least it's part of the flavour vernacular). I used to think that it was just part of the flavour - if you weren't into bitter or sour, then you weren't into coffee. This was partially wrong. Those flavours are always present, but can be optimised. Now I, too look for bitterness and sourness in an effort to describe how much of each is present, in the constant quest to optimise the extraction of the cup.

Every flavour contains four-five basic flavour elements of bitterness, sourness, sweetness and saltiness (and maybe umami, something I read about but on which I'm not an expert). Saltiness (and umami) are not often mentioned in the context of coffee, though are definitely present, but the other three flavour elements are. In summary, everyone's taste preferences lie somewhere along this spectrum of interrelated but distinct flavours:

The coffee extraction flavour spectrum. You can't ever completely isolate bitterness, sweetness or sourness (and why would you), but you can maximise the effect of one along the line.

The flavours above are all inter-related. When searching for 'sour foods' or 'bitter foods' to illustrate, I was pleased to se that lemons and limes show up in both categories. (Coffee, however, only showed up in 'bitter'. Go figure!) Generally I'd suggest, when starting with any new bean, to go along this process (please feel free to suggest adjustments/alternatives)

The above is also an oversimplification. As Matt Perger explained in his recent post on extraction, we're actually targeting optimal extraction, and avoiding under-extraction or over-extraction. I've tried to summarise his article in the chart below:

The balance of extraction in coffee.

Again, the exact point where you are on the chart is entirely subjective, and is something that should be optimised individually. I don't envy the job of roasters and baristas who have to optimise for a crowd of thousands and hope they all like it. Is that even possible?

The below is a rough guide to optimising:

  1. Grind it to a rough 'recommended' grind for your brew method, and brew using your standard method. For example if you use a bog standard french press method, this would be 1mm width coffee grounds, a four minute infusion at 93 degrees before plunging and drinking immediately.
  2. Taste and note down the strength of bitterness, sweetness and sourness. Taste once individually for each one. 
  3. Decide whether you'd like to increase towards bitterness or sourness. For bitterness, extract more, and for sourness, extract less.

For my taste preferences, I am always trying to optimise for sweetness (my subjective interpretation of sweetness, of course). So if something is too sour, I extract more, and if too sweet, I extract less.

On how to extract more or less - more on that coming soon.